1. Field of the Invention
This invention relates to suspension systems for bicycle and moped type vehicles.
2. Description of the Prior Art
Most of the different arrangements now used for bicycle suspension systems are adaptations of motorcycle suspension. Because of the differences between bicycles and motorcycles, however, this approach yields rather limited success. As one illustration of this fact, the need for the rider to pedal a bicycle, and to nearly straighten his or her legs at the bottom of each pedal stroke, makes ground clearance much more of a problem for bicycles than for motorcycles. As a result, maintaining adequate ground clearance with conventional configurations of long-travel suspension would necessitate an excessively high seating position for the rider of a bicycle. Instead, bicycle suspension systems have reduced travel in comparison to the motorcycle type suspension from which they are most often derived.
Since a bicycle rider by himself accounts for the great majority of the overall weight of the bicycle and rider together, the tradeoff between suspension travel and height of the overall center of mass is further compromised. In other words, bicycles already have a very high center of mass when the rider is aboard, and moving the rider's seating position upward a given amount, to thereby provide sufficient ground clearance at full suspension jounce (compression), will elevate the center of mass by an almost equal amount. The same is not true of moving the rider of a motorcycle to a higher seating position because the weight of the machine alone is usually significantly greater than the weight of the rider.
At the same time, the fact that the bicycle itself accounts for only a small portion of its overall operational weight offers an opportunity that motorcycle type of suspension fails to exploit. More specifically, suspending a bicycle frame as well as the rider little changes the overall percentage of weight that remains unsprung, but it causes the geometry of the bicycle frame to change as the suspension system functions. Suspending just the seat of a bicycle does take advantage of the low eight of the bicycle in comparison to the rider, but it also causes the rider to bob up and down with each pedal stroke.